An Introduction to the Tests Used for Lyme Disease Diagnosis

One of the reasons that it’s so difficult to get a Lyme Disease diagnosis, at least in the United States, is because most doctors require positive results from blood and serum tests in the absence of an erythema migrans (EM) rash — the single diagnostic symptom accepted by almost everyone.

There are three common tests for LD: ELISA, Western Blot, and PCR. All look for evidence of Borrelia spirochetes in the bloodstream, though the type of evidence varies from test to test. All three tests have their issues, which we’ll explore briefly in this article.

The ELISA Test

ELISA is an acronym for Enzyme-Linked Immunosorbent Assay, which is more of a category than an individual test. Doctors also use ELISAs to identify HIV and other immunodeficiency ailments. The LD version is only a first-round check for infection, and it’s not a good idea to use it as the sole basis for diagnosis.

Basically, an ELISA test looks for antibodies that your system creates to fight the LD spirochetes. Unfortunately, this test tends to return a lot of false positives, and doesn’t always detect Borrelia antibodies even when they’re present. Also, the low levels of antibodies present early in the disease makes it less useful then.

A Western Blot test should follow any Lyme ELISA test, positive or negative, if the patient remains symptomatic. However, many doctors refuse to go forward with LD testing if an ELISA comes back negative, despite the well-known problems with the test.

The Western Blot Test

Like ELISA, the Western Blot searches for Borrelia-related antibodies; in this case, those antibodies are specific to certain proteins. Most doctors consider an individual who tests positive on the Western Blot as well as the ELISA to have full-fledged LD, and will treat accordingly.

This testing method produces a series of bands on a strip of paper, like the lines on a barcode, which correspond to specific antibody strains. As mentioned earlier, the Western Blot also has significant problems, partly based on the definition of which bands comprise a positive result.

The current standardized guidelines, signed off on by the Centers for Disease Control, are very controversial. They ignore some antibody bands altogether, while dismissing others as minor.

Indeed, the current guidelines often categorize people who lack the proper bands as uninfected, even if other symptoms prove otherwise. Some doctors will even ignore an obvious EM rash if the Western Blot comes back negative.

The PCR Test

PCR is short for “polymerase chain reaction.” This test actually finds pieces of spirochetal DNA, if they’re present, and makes enough copies to proper test them. A PCR test can work even with very low levels of infection, and often comes back positive even when ELISA and Western Blot are negative.

The problem here is that the PCR test works best with fluids drawn from an infected joint or spine; it doesn’t work well at all with blood or even urine. In other words, by the time you get a PCR test, the LD is usually well advanced and more difficult to treat.

And even the PCR test doesn’t work well when DNA levels are very low in joint or cerebrospinal fluids, which can occur when the spirochetes have either burrowed into hard tissues or have encysted themselves.

That said, the PCR method is currently the most accurate test for confirming a Lyme Disease diagnosis, at least within its limited purview.